The present invention relates to an incremental forming method for gradually processing a plate; and, more particularly, the invention relates to an incremental forming method for producing a molded product having a flange in an end portion of a plate.
Conventionally, a molded product having a flange at an end portion of a plate is manufactured by inserting and pressing the plate between a female die and a male die. Since the female die and the male die are required, the price becomes high.
As a means for reducing the number of dies, an incremental forming method has proposed, as shown in FIGS. 18 to 20 in Japanese patent application laid-open publication Hei 11-310371. In this method, an outer periphery of a piece of material is fixed to a female die, the material is pressed with a rod-shaped tool, the rod-shaped tool is moved along an inner peripheral face of the female die, and a sponson processing is incrementally carried out on the plate. On the other hand, in Japanese patent application laid-open publication Hei 10-76321, a plate is subjected to a drawing processing.
The above-described incremental forming method uses only one die, so that it is inexpensive. However, in a manner shown in the above-stated Japanese patent application laid-open publication Hei 11-310371, when a flange is formed at an end portion of the plate, a portion of the plate is left at the outer periphery of the flange. When this plate portion is unnecessary, it is necessary to cut off and remove the outer peripheral portion of the flange. Further, when the flange is formed according to this processing procedure, the angle formed between the flange and the plate bottom is not formed as a rectangular angle. For example, when a cylinder is overlapped and joined to the flange, when the flange is not formed in a rectangular shape, it hard to carry out overlapping welding. Further, it is difficult to form a flange having a high height.
On the other hand, when the flange is formed according to the manner shown in Japanese patent application laid-open publication Hei 10-76321, a wrinkle occurs easily on a comer portion of the flange.
An object of the present invention is to provide an incremental forming method for easily forming a plate in a predetermined shape.
The above-stated object can be attained by an incremental forming method, wherein, under a condition where a piece of material is fixed to a seat arranged inside of a female die, with the piece of material arranged between the female die and a tool member and between the seat and the tool member, and under a condition where an outer end portion of the material is capable of movement in a drawing processing direction, the seat and the tool member are relatively moved in the female die in a drawing processing direction, and the tool member is relatively moved along an inner peripheral face of the female die.